


Something precious.

by RussianSunflower3



Series: Inktober 2017 [19]
Category: Haikyuu!!
Genre: Aquariums, Gen, Inktober 2017, Jellyfish, Mermaids, mermaid
Language: English
Status: Completed
Published: 2017-10-19
Updated: 2017-10-19
Packaged: 2019-01-19 12:08:07
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,865
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12410040
Author URL: https://archiveofourown.org/users/RussianSunflower3/pseuds/RussianSunflower3
Summary: Iwaizumi’s latest employee at his Jelly World Aquarium keeps bringing back incredible things from resource collecting by the ocean front. He doesn’t know how Kunimi keeps finding precious gems, rare crystals, and endangered jellyfish, but he just does!One day, Kunimi accidentally stumbles upon something Iwaizumi has been hiding. A mermaid with a prosthetic tail, too attached to return to the ocean. And now, he supposes, he should show Iwaizumi his secret.





	1. Jelly world.

“Iwaizumi-san, I’m back.” The manager of Jelly World looks up from where he’s sweeping the floor, preparing to open the aquarium, not surprised to see Kunimi entering through the automatic doors with pockets weighed down and a jar of water held in hands, held securely like it’s a precious treasure.

He’s sopping wet, drenched from head to toe. But that’s become a common sight. Iwaizumi stopped asking after the first few weeks, just accepting it as part of Kunimi’s resource collecting method. Who doesn’t enjoy a nice dip in the ocean every now and then?

“What have you brought this time?”

“A flower hat jelly.” Iwaizumi drops the broom in his excitement, appearing in front of Kunimi in the blink of an eye, peering into the jar of water with the enthusiasm of a child.

“An Olindias Formosus?! That’s incredible, Kunimi! I don’t know how you found it, because they should _never_ be this far north, but that’s incredible! Ah, there’s three! There’s three!”

“Do you want me to put them in an empty tank for now?” Sobering up, Iwaizumi stands straight and clears his throat into his sleeve like he wasn’t just having a moment over the rare find.

“Yes. I think we should have a few out back. If you can find a spare tank in the hydrozoa corridor, we’ll transfer them there later.” Even though the flower hat jelly isn’t _technically_ a true jellyfish, Iwaizumi was too enthusiastic about the marine creatures to turn them away. Henceforth, he’d had a spare corridor renovated into the hydrozoa corridor, so he could keep all these specimens and share them with the world.

Kunimi watches him pick up the broom again, sweeping with a skip in his step and whistling a merry tune. He hides a small smile behind his jar of flower hat jellies. Seeing his manager acting like a child is incredibly amusing, especially when he’s usually quite stern and calm.

Even though he was only hired three months ago, Kunimi expects he’s the only person to have seen Iwaizumi that excited so frequently, since he keeps bringing in rare and unusual finds. Many times, when they’ve had longer before opening, Iwaizumi tries to squeeze out the details of how he’s finding them.

Kunimi always taps the side of his nose knowingly and walks off. 

He pays for it by getting the morning shifts the next week. Never let it be said that Iwaizumi Hajime isn’t petty as _fuck_.

As he empties the flower hat jellies into their new, temporary home, he pauses, wondering if maybe he _should_ share the secret. Hmm... No, no. Not yet. As much as he trusts Iwaizumi, he doesn’t think this secret should be shared. Not until he’s seen something of equal value.

“Morning, Kunimi~. Resource collecting again?” The door to the prep room opens as Hanamaki steps in, taking off his coat and wellington boots before he goes into the staff room. He stops to try and peer over Kunimi’s shoulder.

“What are these ones then?” Unlike Iwaizumi and Kunimi, Hanamaki can’t identify the jellyfish just by looking. He’s in charge of their small Elasmobranchii tunnel, filled with sharks, rays, skates, and sawfish. Those, he can identify the species of with just a glance. His favourites are Devil fish and longsnout Butterfly rays. 

It says a lot about his personality.

“Olindias Formosus.”

“... Meaning?”

“Olindias Formosus~.”

“Aww, Kunimi! Don’t be sassy so early in the morning!”

“A flower hat jelly.” Hanamaki coos as he peers at the tiny things – little baby jellyfish that will grow up in the aquarium.

“Cute name. They’re pretty.”

“Mhm. They’ll go in the Hydrozoa corridor.”

“Wait, you mean they’re _not_ jellyfish?!” Kunimi holds back a laugh as Hanamaki stares at the three jellies, glaring like he’s personally accusing them of being Hydrozoa. 

“Technically, no. But they’re still called Jellies anyways.” Dubious, Hanamaki scratches the back of his head and steps away.

“Alright, well... You might wanna get dried off. You’ll catch a cold if you stay like that.” He gestures to Kunimi’s dripping wet clothes and soaked hair, puddles around his shoes. The deadpan stare he gets in return is well worth it, and his lips grow into a smirk.

“Sorry to _dampen_ your mood~.”

“Hanamaki-san, I _will_ put a jellyfish on your face, one day.” Laughing, the Elasmobranchii supervisor waves a hand in dismissal, ducking into the changing rooms to get into uniform. Kunimi sighs and tugs over a stool so he can sit down and watch the flower hat jellies for now.

He smiles. Just a small, faint smile, but a smile all the same. Watching them reminds him of how they came into his possession, from the waterside to the aquarium. Although he would quite like it if he could stop being submerged all the time.

As he’s deep in thought, there’s a chime through the speakers. The aquarium is open for business, Matsukawa attending the ticket desk. With another heavy sigh, Kunimi goes into the changing rooms, grabbing a spare bag from his locker with clean, dry clothes and a towel in.

“I’m heading out. See you on lunch break!”

“Will do, Hanamaki-san.” Always on the go, Hanamaki is off, whistling a merry tune. His musical glee is infectious, and Kunimi finds himself humming under his breath as he gets into uniform, towels off his hair and brushes it, before making his way to the Hydrozoa corridor.

He doesn’t do much. Sweeps up the odd patch here and there, answers questions that kids may ask him, and gives an educational talk once every hour. It’s a good job, one that he’s always been interested in, and one that he loves.

For the next few weeks, he spends more and more time resource collecting, stopping by the aquarium even when he’s not on shift, much to Iwaizumi’s amazement. Sometimes, Kunimi buys a ticket with his staff discount and walks around for hours, taking his time to appreciate the marine life like he can’t do on shift.

Matsukawa sometimes jokes that he must be an ocean baby, since he’s always in the aquarium or by the waterside. Kunimi always shrugs and smiles knowingly.

It’s a Tuesday four weeks later when he’s strolling towards the large jellyfish exhibit for their Moon Jellies, a huge circular window about three times as tall as him. It’s the main attraction of their aquarium, and it’s _beautiful_.

“Do you think mermaids are real, mister?” He grinds to a halt, throwing himself back against a wall before anyone in the room can see him enter. He peers back around to see Iwaizumi crouch down in front of a small child holding a mermaid helium balloon.

“You wanna know the truth? The _reeeeeal_ truth?” The child nods, and with a playful slyness, Iwaizumi looks around the room as if to make sure no one is listening in before putting one hand up to his mouth and whisper-shouting.

“Mermaids are _definitely_ real.” Kunimi thinks that maybe, just maybe, Iwaizumi is saying it so there won’t be a breakout of tears. But... Something about his voice is so enthusiastic and _honest_... It’s like when Kunimi brings rare jellyfish in. He really, truly knows what he’s saying.

“They are?”

“Mhm~. It’s a big ocean out there, and I bet there are _tons_ of mermaids living in their family groups and hiding from prying eyes.”

“Why hide?” Kunimi watches as Iwaizumi’s lips twitch into a frown, and his eyes lose that brightness.

“There are bad people who hurt mermaids out there. They have to stay safe by staying hidden.” He blinks, as if shaking off a haze, and grins at the kid, pressing a finger over his lips.

“Keep it a secret, okay~?” Kunimi lingers a second longer. He _could_ just casually walk in like he’s only just arrived, but... Something about the tone of Iwaizumi’s voice makes him want to wait. To see what happens next. He hears the jingle of keys. 

Brow furrowed, he peers back around the wall, and is flooded with _betrayal_. See, there’s a door in the Moon Jellies room that Kunimi had been told was ‘for decorative purposes only’. It was even painted the same colour as the wall, like it had never been opened.

But here, right in front of his spying eyes, Iwaizumi unlocks and opens the door. Kunimi huffs under his breath, waiting until Iwaizumi vanishes from sight to slip out and follow after. Much to his delight, the slowly closing door is open just enough for him to stick a pen in the gap.

He holds it until the footsteps inside are far enough away and then he peers in.

“It’s okay, I know you’re there.” Kunimi clicks his tongue in irritation, slipping the door open further and stepping in, Iwaizumi smiling at him smugly with hands in pockets, almost glowing as he stands in front of a huge tank of pure blue water, a coral reef at the bottom and long seaweed grass around the edges.

“How did you know?”

“You’ve got jars in your pockets. They tend to make a noise when they hit the wall~.” Scowling, Kunimi steps to Iwaizumi’s side. He glances up at the large, supposedly empty aquarium wall.

“What’s this tank for?” Amused, Iwaizumi slaps a hand on his back, pushing him closer.

“I originally was going to wait until you’d been here a year before showing you, but since you overheard my conversation, I think you’re ready.” Before Kunimi can even form the words in his head to ask what Iwaizumi means, there’s movement within the tank, long sea grass rustling.

Kunimi thinks he spots a flash of teal, and looks questioningly to Iwaizumi, who only nods and pushes him closer towards the tank.

“I- I don’t under-... Stand...” He trails off as a face comes into view, but it’s not his reflection in the glass, it’s someone on the _other_ side. He swallows, eyes scanning what’s in front of him as if he doubts it.

A mermaid. Brown hair that flows freely in the water, matching brown eyes like driftwood, with golden speckles. A teal tail with aqua patches, long fins like a Beta fish, and-

Part of the tail replaced by a prosthetic. Kunimi glances over his shoulder at Iwaizumi, who sighs and steps to his side, pressing a hand to the glass. The mermaid presses his own webbed hand back, grinning happily.

“This is Oikawa. He’s been my best friend since I found him 7 years ago. He was injured – harpooned – but my dad and I managed to treat him, kept him in a bathtub, and built him a new tail. The only problem was, after all that we’d been through together, he refused to go back in the ocean.”

“Well, it’s not like I had anyone to _return_ to! The Hunters killed my pack!” At the scoff and snappy reply, Kunimi jumps backwards in surprise. Japanese. The mermaid speaks _Japanese_.

“You- You can talk. You can talk human languages.” The mermaid flips his hair, bottom lip jutting out as he looks down his nose at Kunimi.

“Well, duh. Iwa-chan was too thick-headed to learn mine, so I learnt his.”

“That’s a lie and you damn know it, Shittykawa! You didn’t even _try_ and teach me!”

“Because you were so slow! You couldn’t learn in 4 weeks what hatchlings learn in a day!” Whilst they argue, Kunimi stares. Kunimi stares, partially aware of Oikawa moving in an elegant figure of eight, but mostly fixed in his thoughts.

Iwaizumi believes in mermaids.

Iwaizumi is _best friends_ with a mermaid.

“Kunimi?” The hand on his shoulder jolts him out of his daze, and he gives Iwaizumi a small, reassuring smile before turning to Oikawa, who peers at him in interest.

“You’re young, aren’t you?” Kunimi tilts his head, opens his mouth to answer, then stops. He takes a deep breath, closes his eyes, and _clicks_. Oikawa’s eyes widen, his tail pausing in movement for a split second. 

Then, he’s pressing himself against the glass, all sunshine and rainbows and enthusiasm.

“Where did you learn that?!” Iwaizumi looks between them in confusion as Kunimi whistles something back, and then Oikawa makes noises vaguely like a dolphin, until the two of them are just making _sounds_.

“What- What’s going on?”

“This kid can speak my language! He speaks my pack language!!!” Kunimi shrugs, slightly blushing and a little guilty as Iwaizumi gapes at him, pointing slowly between Oikawa and Kunimi.

“You-... His...? How?” 

All this time, Kunimi has been waiting for a secret of equal value to show Iwaizumi how he manages to collect rare jellyfish, crystals and items from the seafloor. His eyes glance briefly at Oikawa, at a _mermaid_ , and he decides that yes, this is it. This is the secret of equal value, and it’s time to unveil his trick to the aquarium manager.

“I have something to show you... And someone I’d like you to meet.”


	2. Rock Pools

“Alright, we’re locked up. So, what did you want to show us?” Hanamaki slings an arm around Kunimi’s shoulders, which the boy pushes off with an expression of deadpan disgust. Having caught the duo stepping out of Oikawa’s basement, Hanamaki and Matsukawa had instantly wheedled information out of them, concerning where they were talking about going after work.

“Actually, I was only going to show _Iwaizumi-san_.” Hanamaki makes the most ridiculous puppy-dog eyes and Kunimi can’t help by hide a snort of amusement.

“Maybe next time. My friend is... Kind of shy.” Matsukawa huffs under his breath, tugging Hanamaki back by his collar. Being somewhat shy himself, Matsukawa can understand why Kunimi doesn’t want to suddenly introduce his friend to _three_ people.

“C’mon. We’ll go to the bakery instead.”

“Ooh, yeah, let’s go!” Hanamaki starts walking towards their car, and Matsukawa rolls his eyes in affection before following after him, raising a hand to bid goodbye to Kunimi and Iwaizumi. They wave back, watching as the car disappears down the only road to the aquarium.

“Where did your friend want to meet us?”

“By the rockpools.” Iwaizumi quirks an eyebrow and Kunimi tries not to give anything away, but he’s pretty sure Iwaizumi has already clocked on.

“So _that’s_ how you speak mermaid.”

“You could say that. But there’s more than one mermaid language. Each region has their own language, like how countries have different languages, and then each pack has their own dialect.”

“But... Oikawa said all his pack were killed by Hunters... How could you know his dialect?” Kunimi humms under his breath, quickening his pace towards the rockpools.

“Mhm, that’s what I was thinking when he said it. I came to the conclusion that maybe, just maybe, he might be wrong.” Iwaizumi frowns deeply by his side.

“I- I don’t know, Kunimi. He’s always honest when he talks about it. He was pretty traumatized.”

“Mhm. That’s why I’m sure that it was a _mistake_. Oikawa-san must have been entirely sure that his pack were hunted, but one of them, just one, might have escaped. My friend is... Young. Around my age. He could have been ‘hatched’ after you found Oikawa-san.”

“That’s... Possible.” The rockpools soon come into view. Technically, they aren’t rock pools at all, but a large open cavern facing the sea that’s filled with round, pond-like water holes. Some of them have a green spray-painted cross next to them.

“I’d recommend standing with your back against the wall.” Confused, Iwaizumi shuffled back so that his back presses flat against the one large wall, peering out into the ocean between the two columns on the edge of the earth, clay and stone standing strong to keep this area sheltered. 

Carefully, Kunimi steps around the pools, making sure he isn’t in front of one with a green ‘x’ on the side. Those, he marked himself. They’re connected to the ocean, and there’s a good reason he marked them.

“Ah, depending how far away he is, we might be waiting a few minutes.”

“I’m okay with that.” Rummaging in his pockets, brushing asides jars and nimbly picking through crystals, Kunimi picks out a tiny set of bamboo panpipes. He takes a deep breath, presses his lips over the second to smallest pipe, and blows.

The piercing whistle echoes out far and wide, and Iwaizumi winces. Some warning would have been nice. Kunimi lowers the panpipes, steadying his breath.

“Now we wait.” The ocean is calm, lapping at the shore and splashing into the pools at the front with the usual noise, and Kunimi stands where he is patiently, waiting. After about 5 minutes, Iwaizumi shuffles to sit down. His legs ache after a long day of work, and this peaceful moment makes him want to relax.

He’s starting to lose hop of meeting Kunimi’s friend when he suddenly spots something in one of the pools, one that isn’t marked by an ‘x’. The shadow moves, and then slowly, not risking making a single splash, the thing pokes above the water. 

From behind, Iwaizumi can’t see the playful, excited expression, but he can _sense_ it. It’s in the way the mermaid wiggles his dark red tail, the way he leans into the side of the pool, and how he sinks back into the water. Iwaizumi nearly leans over to peer in, but then-

The mermaid launches himself out of the pool with an enthusiastic squeal, and Kunimi only _just_ has time to turn around and spot him before he and the mermaid go splashing into the open ocean. Iwaizumi laughs, clutching at his stomach as Kunimi appears again, spitting water out with an annoyed, deadpan expression.

“So _that’s_ why you’re always drenched!”

“Do me a favour and tell me which one he came out of.” Whilst Iwaizumi points, the mermaid with black hair and dark red tail circles around Kunimi, keeping him against the rock so the current of the ocean doesn’t pull him away. He clambers up onto the rock again, plonking himself on the edge with his feet still in the water.

The mermaid trills, moving to cross his arms over Kunimi’s knees, grinning up at him cheekily. Kunimi smirks and pats his cheeks, before resting his hands on the mermaid’s shoulders. He chirps and whistles back, and Iwaizumi watches as the mermaid peers over Kunimi’s shoulder, then sinks down in the water until only his eyes are above the waves.

Iwaizumi waves a little, but that only seems to make matters worse as the mermaid ducks behind Kunimi with little noises that are obviously distressed. Kunimi talks with him for a moment – reassuring him that he won’t be hurt, Iwaizumi is safe, there is no danger here- and finally, the mermaid pulls himself half-up onto the land.

“This is Kindaichi. Say hello, Iwaizumi-san.”

“H-Hey? Uh, hello, Kindaichi?” The mermaid stares at him intensely. Then, he blows a bubble. As Iwaizumi watches it float to the ceiling, there’s a splash and he snaps his gaze downwards to see ripples in one of the other pools, the mermaid missing. Kunimi huffs.

“I’m guessing he doesn’t like me, huh?”

“Like I told Hanamaki-san, he’s shy.” He seems to pause, nibbling on his bottom lip, head hanging low in guilt as he moves to stand up.

“Actually... You’re the first person I’ve introduced him to. I think, uh, I think he thought I was the only one.” Sighing, Iwaizumi stands, rubbing the back of his head.

“That’s understandable. If, like you said, he’s the only mermaid here, he might have thought there was only one human here too.”

“Mhm... Thank you, for understanding.” Just as they’re about to leave, there’s a happy little squeak behind them. They turn to see three jars filled with water sitting on the edge of one of the pools, right in front of Kindaichi, who flicks his tail to splash water in Iwaizumi’s direction.

“... I think he likes you~.” Laughing as he wipes the water away with his sleeve, Iwaizumi moves back over to pick up the jars as Kunimi gestures for him to. It’s as he peers in that he realises they’re not just jars of water.

“Woah! That’s a cephea cephea!!! And this one is a Coronate Medusa!!! Kunimi, look! More Chrysaora pacifica to add to the aquarium!” Iwaizumi rotates through the jars, fawning over them like a child at Christmas, and Kunimi muffles a laugh as Kindaichi watches in absolute glee, chirruping and squeaking along as if he understands the words. He doesn’t, but he knows the warm, excited tone means something good.

“Now you know who helps me with resource collecting~.” Iwaizumi breathes out in awe, looking straight at Kindaichi.

“You’re amazing, y’know? Incredible.” The mermaid tilts his head, not understanding. But then, something else catches his eye. With a coo, Kindaichi suddenly lunged upwards so he’s flopped _over_ Iwaizumi, partially crushing him under the weight of his massive tail, as he reaches up and runs his hands through Iwaizumi’s hair, tugging at the spikes.

“Uh.” Iwaizumi, completely caught off guard, blinks with a stunned and bewildered expression. It’s enough to make Kunimi laugh, trying to hide it in his sleeve. Kindaichi grins, ruffling the short, spiky hair. He lifts up a couple strands of his own, confused and frustrated when they don’t stick.

“Is he- Is he trying to imitate my hair?”

“I believe he is~. I’ll explain it tomorrow. We should get those jellies back to the aquarium.” Iwaizumi blinks. He pats Kindaichi on the head. The mermaid looks at him, blushes, and darts back into the pool.

“Did I do something wrong?”

“No, he’s just shy. He probably realised he was invading your personal space and got flustered.” Iwaizumi pushes himself up and brushes off, collecting up the three jars. Kunimi takes two from him, putting them in his pockets, but he lets Iwaizumi cradle the Coronate Medusa, like it’s the most precious gift he’s ever received. They 

“I’ll bring my hair gel along next time, if he wants to try it. Not sure it would last too long underwater though...” Kunimi stumbles, literally tripping over words, eyes wide as he looks back to his manager.

“Next time? You mean it?” Iwaizumi grins, giving Kunimi that 1000 watt smile that was contagious.

“Of course I do! Mermaids are cool, but the fact that he could be Oikawa’s _family_? That means I just have to get to know him!” Kunimi hides a small smile by ducking his head down, fringe falling over his face.

“I really hope he is. He must be lonely most of the time.” Kunimi remembers how Kindaichi tells him of making ‘friends’ with polyps and coral, various fish and a few crustaceans. The only one who spoke his language was Kunimi, and even then, he was laconic. It would be impossible for Kindaichi to have a full conversation with anyone else when Kunimi wasn’t there.

“Y’know... I’m wondering if I can build a slipway onto Oikawa’s tank... _He_ can’t swim in the ocean, but Kindaichi can swim in a tank...” 

“R-Really? That would be... That would be amazing...” Iwaizumi nudges his shoulder against Kunimi.

“No problem~.”

Kunimi just hopes tomorrows adventure with hair gel goes as well as the initial introduction.

**Notes for the Chapter:**

> Please kudos/comment~!

**Author's Note:**

> Dun dundun!!!! Who could Kunimi possibly be introducing? 
> 
> 19th October!!! Inktober is really blazing along!!!!  
> I'm so short on time but I still made this multi-chapter. ...Oops.
> 
> Please Kudos and **Comment**!!!!


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